/********************************************************************************
 * Copyright (c) 2011-2017 Red Hat Inc. and/or its affiliates and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 1.0 which is available at
 * http://www.eclipse.org/legal/epl-v10.html.
 *
 * SPDX-License-Identifier: EPL-1.0
 ********************************************************************************/
package org.eclipse.ceylon.ide.eclipse.code.html;

import static org.eclipse.ceylon.ide.eclipse.util.EditorUtil.createColor;
import static org.eclipse.ceylon.ide.eclipse.util.Highlights.DOC_BACKGROUND;
import static org.eclipse.ceylon.ide.eclipse.util.Highlights.getCurrentThemeColor;
import static org.eclipse.ui.texteditor.AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND_SYSTEM_DEFAULT;
import static org.eclipse.ui.texteditor.AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND;
import static org.eclipse.ui.texteditor.AbstractTextEditor.PREFERENCE_COLOR_FOREGROUND_SYSTEM_DEFAULT;

import java.io.IOException;
import java.io.Reader;
import java.net.URL;

import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.text.DefaultInformationControl;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.internal.editors.text.EditorsPlugin;

/**
 * Provides a set of convenience methods for creating HTML pages.
 * <p>
 * Moved into this package from <code>org.eclipse.jface.internal.text.revisions</code>.</p>
 */
public class HTMLPrinter {

//    private static RGB BG_COLOR_RGB= new RGB(255, 255, 225); // RGB value of info bg color on WindowsXP
//    private static RGB FG_COLOR_RGB= new RGB(0, 0, 0); // RGB value of info fg color on WindowsXP
    
//    private static final String UNIT; // See https://bugs.eclipse.org/bugs/show_bug.cgi?id=155993
//    static {
//        UNIT= Util.isMac() ? "px" : "pt";   //$NON-NLS-1$//$NON-NLS-2$
//    }


//    static {
//        final Display display= Display.getDefault();
//        if (display != null && !display.isDisposed()) {
//            try {
//                display.asyncExec(new Runnable() {
//                    /*
//                     * @see java.lang.Runnable#run()
//                     */
//                    public void run() {
//                        cacheColors(display);
//                        installColorUpdater(display);
//                    }
//                });
//            } catch (SWTError err) {
//                // see https://bugs.eclipse.org/bugs/show_bug.cgi?id=45294
//                if (err.code != SWT.ERROR_DEVICE_DISPOSED)
//                    throw err;
//            }
//        }
//    }

    private HTMLPrinter() {
    }

//    private static void cacheColors(Display display) {
//        BG_COLOR_RGB= display.getSystemColor(SWT.COLOR_INFO_BACKGROUND).getRGB();
//        FG_COLOR_RGB= display.getSystemColor(SWT.COLOR_INFO_FOREGROUND).getRGB();
//    }
//    
//    private static void installColorUpdater(final Display display) {
//        display.addListener(SWT.Settings, new Listener() {
//            public void handleEvent(Event event) {
//                cacheColors(display);
//            }
//        });
//    }
    
    private static String replace(String text, char c, String s) {

        int previous= 0;
        int current= text.indexOf(c, previous);

        if (current == -1)
            return text;

        StringBuilder buffer= new StringBuilder();
        while (current > -1) {
            buffer.append(text.substring(previous, current));
            buffer.append(s);
            previous= current + 1;
            current= text.indexOf(c, previous);
        }
        buffer.append(text.substring(previous));

        return buffer.toString();
    }

    /**
     * Escapes reserved HTML characters in the given string.
     * <p>
     * <b>Warning:</b> Does not preserve whitespace.
     * 
     * @param content the input string
     * @return the string with escaped characters
     * 
     * @see #convertToHTMLContentWithWhitespace(String) for use in browsers
     * @see #addPreFormatted(StringBuilder, String) for rendering with an {@link HTML2TextReader}
     */
    public static String convertToHTMLContent(String content) {
        content= replace(content, '&', "&amp;"); //$NON-NLS-1$
        content= replace(content, '"', "&quot;"); //$NON-NLS-1$
        content= replace(content, '<', "&lt;"); //$NON-NLS-1$
        return replace(content, '>', "&gt;"); //$NON-NLS-1$
    }

    /**
     * Escapes reserved HTML characters in the given string
     * and returns them in a way that preserves whitespace in a browser.
     * <p>
     * <b>Warning:</b> Whitespace will not be preserved when rendered with an {@link HTML2TextReader}
     * (e.g. in a {@link DefaultInformationControl} that renders simple HTML).

     * @param content the input string
     * @return the processed string
     * 
     * @see #addPreFormatted(StringBuilder, String)
     * @see #convertToHTMLContent(String)
     * @since 3.7
     */
    public static String convertToHTMLContentWithWhitespace(String content) {
        content= replace(content, '&', "&amp;"); //$NON-NLS-1$
        content= replace(content, '"', "&quot;"); //$NON-NLS-1$
        content= replace(content, '<', "&lt;"); //$NON-NLS-1$
        content= replace(content, '>', "&gt;"); //$NON-NLS-1$
        return "<span style='white-space:pre'>" + content + "</span>"; //$NON-NLS-1$ //$NON-NLS-2$
    }
    
    public static String read(Reader rd) {

        StringBuilder buffer= new StringBuilder();
        char[] readBuffer= new char[2048];

        try {
            int n= rd.read(readBuffer);
            while (n > 0) {
                buffer.append(readBuffer, 0, n);
                n= rd.read(readBuffer);
            }
            return buffer.toString();
        } catch (IOException x) {
        }

        return null;
    }

    public static void insertPageProlog(StringBuilder buffer, int position, RGB fgRGB, RGB bgRGB, String styleSheet) {
        if (fgRGB == null)
            fgRGB= fg();
        if (bgRGB == null)
            bgRGB= bg();

        StringBuilder pageProlog= new StringBuilder(300);

        pageProlog.append("<html>"); //$NON-NLS-1$

        appendStyleSheet(pageProlog, styleSheet);

        appendColors(pageProlog, fgRGB, bgRGB);

        buffer.insert(position,  pageProlog.toString());
    }

    protected static RGB bg() {
        return getSystemColor(SWT.COLOR_INFO_BACKGROUND);
    }

    protected static RGB getSystemColor(final int systemColor) {
        final RGB[] rgb = new RGB[1];
        Display.getDefault().syncExec(new Runnable() {
            
            @Override
            public void run() {
                rgb[0] = Display.getDefault().getSystemColor(systemColor).getRGB();
            }
        }); 
        return rgb[0];
    }

    protected static RGB fg() {
        return getSystemColor(SWT.COLOR_INFO_FOREGROUND);
    }

    private static void appendColors(StringBuilder pageProlog, RGB fgRGB, RGB bgRGB) {
        pageProlog.append("<body");
        if (fgRGB!=null) {
            pageProlog.append(" text=\""); //$NON-NLS-1$
            appendColor(pageProlog, fgRGB);
        }
        if (bgRGB!=null) {
            pageProlog.append("\" bgcolor=\""); //$NON-NLS-1$
            appendColor(pageProlog, bgRGB);
            pageProlog.append("\"");
        }
        pageProlog.append(">"); //$NON-NLS-1$
    }
    
    public static String toHex(Color color) {
        StringBuilder buffer = new StringBuilder();
        if (color!=null) {
        	appendColor(buffer, color.getRGB());
        }
        return buffer.toString();
    }
    
    private static void appendColor(StringBuilder buffer, RGB rgb) {
        buffer.append('#');
        appendAsHexString(buffer, rgb.red);
        appendAsHexString(buffer, rgb.green);
        appendAsHexString(buffer, rgb.blue);
    }

    private static void appendAsHexString(StringBuilder buffer, int intValue) {
        String hexValue= Integer.toHexString(intValue);
        if (hexValue.length() == 1)
            buffer.append('0');
        buffer.append(hexValue);
    }

    public static void insertStyles(StringBuilder buffer, String[] styles) {
        if (styles == null || styles.length == 0)
            return;

        StringBuilder styleBuf= new StringBuilder(10 * styles.length);
        for (int i= 0; i < styles.length; i++) {
            styleBuf.append(" style=\""); //$NON-NLS-1$
            styleBuf.append(styles[i]);
            styleBuf.append('"');
        }

        // Find insertion index
        // a) within existing body tag with trailing space
        int index= buffer.indexOf("<body "); //$NON-NLS-1$
        if (index != -1) {
            buffer.insert(index+5, styleBuf);
            return;
        }

        // b) within existing body tag without attributes
        index= buffer.indexOf("<body>"); //$NON-NLS-1$
        if (index != -1) {
            buffer.insert(index+5, ' ');
            buffer.insert(index+6, styleBuf);
            return;
        }
    }

    private static void appendStyleSheet(StringBuilder buffer, String styleSheet) {
        if (styleSheet == null)
            return;
        
        // workaround for https://bugs.eclipse.org/318243
        StringBuilder fg= new StringBuilder();
        appendColor(fg, fg());
        styleSheet= styleSheet.replaceAll("InfoText", fg.toString()); //$NON-NLS-1$
        StringBuilder bg= new StringBuilder();
        appendColor(bg, bg());
        styleSheet= styleSheet.replaceAll("InfoBackground", bg.toString()); //$NON-NLS-1$

        buffer.append("<head><style CHARSET=\"ISO-8859-1\" TYPE=\"text/css\">"); //$NON-NLS-1$
        buffer.append(styleSheet);
        buffer.append("</style></head>"); //$NON-NLS-1$
    }

    private static void appendStyleSheetURL(StringBuilder buffer, URL styleSheetURL) {
        if (styleSheetURL == null)
            return;

        buffer.append("<head>"); //$NON-NLS-1$

        buffer.append("<LINK REL=\"stylesheet\" HREF= \""); //$NON-NLS-1$
        buffer.append(styleSheetURL);
        buffer.append("\" CHARSET=\"ISO-8859-1\" TYPE=\"text/css\">"); //$NON-NLS-1$

        buffer.append("</head>"); //$NON-NLS-1$
    }

    public static void insertPageProlog(StringBuilder buffer, int position) {
        StringBuilder pageProlog= new StringBuilder(60);
        pageProlog.append("<html>"); //$NON-NLS-1$
        appendColors(pageProlog, fg(), bg());
        buffer.insert(position,  pageProlog.toString());
    }

    public static void insertPageProlog(StringBuilder buffer, int position, URL styleSheetURL) {
        StringBuilder pageProlog= new StringBuilder(300);
        pageProlog.append("<html>"); //$NON-NLS-1$
        appendStyleSheetURL(pageProlog, styleSheetURL);
        appendColors(pageProlog, fg(), bg());
        buffer.insert(position,  pageProlog.toString());
    }

    public static void insertPageProlog(StringBuilder buffer, int position, String styleSheet) {
    	Color fg = null, bg = null;
        IPreferenceStore editorPreferenceStore = 
        		EditorsPlugin.getDefault().getPreferenceStore();
		if (!editorPreferenceStore.getBoolean(
				PREFERENCE_COLOR_BACKGROUND_SYSTEM_DEFAULT)) {
		    bg = getCurrentThemeColor(DOC_BACKGROUND);
//			bg = createColor(editorPreferenceStore, 
//        				PREFERENCE_COLOR_BACKGROUND);
		}
		if (!editorPreferenceStore.getBoolean(
				PREFERENCE_COLOR_FOREGROUND_SYSTEM_DEFAULT)) {
			fg = createColor(editorPreferenceStore, 
        				PREFERENCE_COLOR_FOREGROUND);
		}
        insertPageProlog(
        		buffer, position, 
        		fg==null ? null : fg.getRGB(), 
        		bg==null ? null : bg.getRGB(), 
        		styleSheet);
    }

    public static void addPageProlog(StringBuilder buffer) {
        insertPageProlog(buffer, buffer.length());
    }

    public static void addPageEpilog(StringBuilder buffer) {
        buffer.append("</body></html>"); //$NON-NLS-1$
    }

    public static void startBulletList(StringBuilder buffer) {
        buffer.append("<ul>"); //$NON-NLS-1$
    }

    public static void endBulletList(StringBuilder buffer) {
        buffer.append("</ul>"); //$NON-NLS-1$
    }

    public static void addBullet(StringBuilder buffer, String bullet) {
        if (bullet != null) {
            buffer.append("<li>"); //$NON-NLS-1$
            buffer.append(bullet);
            buffer.append("</li>"); //$NON-NLS-1$
        }
    }

    public static void addSmallHeader(StringBuilder buffer, String header) {
        if (header != null) {
            buffer.append("<h5>"); //$NON-NLS-1$
            buffer.append(header);
            buffer.append("</h5>"); //$NON-NLS-1$
        }
    }

    public static void addParagraph(StringBuilder buffer, String paragraph) {
        if (paragraph != null) {
            buffer.append("<p>"); //$NON-NLS-1$
            buffer.append(paragraph);
        }
    }

    /**
     * Appends a string and keeps its whitespace and newlines.
     * <p>
     * <b>Warning:</b> This starts a new paragraph when rendered in a browser, but
     * it doesn't starts a new paragraph when rendered with a {@link HTML2TextReader}
     * (e.g. in a {@link DefaultInformationControl} that renders simple HTML).
     * 
     * @param buffer the output buffer
     * @param preFormatted the string that should be rendered with whitespace preserved
     * 
     * @see #convertToHTMLContent(String)
     * @see #convertToHTMLContentWithWhitespace(String)
     * @since 3.7
     */
    public static void addPreFormatted(StringBuilder buffer, String preFormatted) {
        if (preFormatted != null) {
            buffer.append("<pre>"); //$NON-NLS-1$
            buffer.append(preFormatted);
            buffer.append("</pre>"); //$NON-NLS-1$
        }
    }

    public static void addParagraph(StringBuilder buffer, Reader paragraphReader) {
        if (paragraphReader != null)
            addParagraph(buffer, read(paragraphReader));
    }

    /**
     * Replaces the following style attributes of the font definition of the <code>html</code>
     * element:
     * <ul>
     * <li>font-size</li>
     * <li>font-weight</li>
     * <li>font-style</li>
     * <li>font-family</li>
     * </ul>
     * The font's name is used as font family, a <code>sans-serif</code> default font family is
     * appended for the case that the given font name is not available.
     * <p>
     * If the listed font attributes are not contained in the passed style list, nothing happens.
     * </p>
     *
     * @param styles CSS style definitions
     * @param fontData the font information to use
     * @return the modified style definitions
     * @since 3.3
     */
//    public static String convertTopLevelFont(String styles, FontData fontData) {
//        boolean bold= (fontData.getStyle() & SWT.BOLD) != 0;
//        boolean italic= (fontData.getStyle() & SWT.ITALIC) != 0;
//        String size= Integer.toString(fontData.getHeight()) + UNIT;
//        String family= "'" + fontData.getName() + "',sans-serif"; //$NON-NLS-1$ //$NON-NLS-2$
//        
//        styles= styles.replaceFirst("(html\\s*\\{.*(?:\\s|;)font-size:\\s*)\\d+pt(\\;?.*\\})", "$1" + size + "$2"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
//        styles= styles.replaceFirst("(html\\s*\\{.*(?:\\s|;)font-weight:\\s*)\\w+(\\;?.*\\})", "$1" + (bold ? "bold" : "normal") + "$2"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
//        styles= styles.replaceFirst("(html\\s*\\{.*(?:\\s|;)font-style:\\s*)\\w+(\\;?.*\\})", "$1" + (italic ? "italic" : "normal") + "$2"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
//        styles= styles.replaceFirst("(html\\s*\\{.*(?:\\s|;)font-family:\\s*).+?(;.*\\})", "$1" + family + "$2"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
//        return styles;
//    }
}
